The present invention relates generally to moving an object through a medium using a magnetic field and, more particularly, to an apparatus and method for controlling the movement of an object through a medium using a magnetic field produced by energized coils by controlling the current in the coils to vary the magnetic field.
The use of a magnetic field to move objects through a medium is known in the prior art. This type of technology has been used in stereotaxic applications to direct instruments, implants and medication to a specific locus in the brain. Examples of such stereotaxic applications are described in U.S. Pat. No. 6,128,174 (Ritter et al.), U.S. Pat. No. 6,015,414 (Werp et al.), U.S. Pat. No. 5,654,864 (Ritter et al.), U.S. Pat. No. 5,125,888 (Howard et al.), and U.S. Pat. No. 4,869,247 (Howard, III et al.), the entire disclosures of which are incorporated herein by reference. In prior stereotaxic applications, however, the magnetic field for moving the object through a patient's body part is changed by either moving the magnet around the patient's body part or by moving the patient. These methods are impractical, especially where large magnets are used to obtain higher magnetic fields. Another prior art method includes placing the patient's head within an electromagnetic coil or between a number of electromagnetic coils and changing the coils' current magnitude and direction. This method is impractical because the coil restricts access to the patient's head, which impedes surgery.
As recognized by the inventor hereof, what is needed is a cost effective apparatus and method that controls the movement of an object through a medium, such as a patient's brain, using a variable magnetic field produced by a magnet at a certain range from a patient such that neither the magnet nor patient need to be moved and such that access to the patient is not impeded by the magnet apparatus.